Development fog is a phenomenon in which the density on the unexposed portion of a silver halide photographic material (hereinafter simply referred to as "light-sensitive material") increases during development. The higher the sensitivity of the light-sensitive material is, the more easily occurs this phenomenon. The longer the light-sensitive material is stored, the more easily occurs this phenomenon. The higher the temperature and humidity at which the light-sensitive material is stored, the more easily occurs this phenomenon.
In order to reduce the time to completion of processing, high temperature rapid processing or high activity rapid processing is often effected to reduce the processing time. In this case, too, fog occurs quite often. Development fog causes deterioration in photographic properties such as image contrast. Therefore, it is desired to inhibit development fog as much as possible.
In order to inhibit development fog, an approach has heretofore been employed which comprises the incorporation of a so-called antifogging agent in light-sensitive materials. As such antifogging agents there have been known many compounds as disclosed in Birr, "Stabilization of Photographic Silver Halide Emulsions", Focal Press, (1974). However, there has arisen a problem that as the antifogging agent inhibits fog more strongly, it decreases sensitivity, lowering gradation, or inhibits the adsorption of a sensitizing dye, hindering color sensitization. It has been thus desired to provide a compound which inhibits fog while enabling the maintenance of sensitivity and gradation without deteriorating color sensitization.
Methods for improving an image contract in high temperature processing are disclosed, for example, in JP-A-59-168442, JP-A-59-111636, JP-A-59-177550, JP-A-60-168545, JP-A-60-180199, JP-A-60-180563, JP-A-61-53633, JP-A-62-78554, JP-A-62-123456, JP-A-63-133144, JP-A-2-44336, Japanese Patent Application No. Hei. 1-33338, but satisfactory effects were not obtained by these methods.